This invention relates to the field of tube connectors, and more particularly to a sweep elbow tube connector and technique for fabrication.
Tube connectors fabricated by injection molding techniques are in common use. One type of connector is a 90 degree connector, which provides a sharp 90 degree angle transition, and can be fabricated by use of two core pins with a mold. With the core pins oriented at a 90 degree angle relative to each other, and arranged relative to a mold, the connector is readily fabricated by injecting the molten material into the mold, and thereafter withdrawing the core pins applying an extraction force on the pins along the pin axis. A compact connector can be fabricated in this way.
A problem with this known type of connector is due to the right angle junction of the tube connector. This results in poor laminar flow of a fluid passing through the connector. For some applications involving viscous fluids passing through the connector, this can lead to build-up of the fluid in the comer of the tube connector, and significant pressure drops through the connector. A right angle connector provides the greatest pressure drop of any tubing connector in common use. Since equipment using the connector typically uses many connectors in a complex arrangement, this can lead to significant down time and expense in removing the 90 degree connectors and cleaning the unwanted deposits.
It would therefor represent an advance in the art to provide an improved 90 degree tube connector which is not susceptible to fluid build-up and deposits.
It would further be advantageous to provide a tube connector which does not require frequent removal and cleaning.
A molded sweep elbow tube connector is described, and includes a molded tube connector member comprising a first linear tube end portion, a second linear tube end portion, and a curved sweep tube portion defined by a relatively large sweep radius and joining the two end portions to form an integral one-piece molded part. The tube connector member forms an interior passageway for carrying a flow of fluid, characterized by a sweep bend between the two end portions, permitting fluid laminar flow through the tube connector. The tube connector member has a thick wall thickness over at least a portion of the curved sweep tube portion and a thin wall thickness over the first linear tube end. The thin wall thickness facilitates the removal of a curved core pin from the part through a linear tube end portion after injection molding, since the plastic material will flex enough to permit the pin to be stripped without damaging the part.
The tube connector has a first connector structure at the first tube end portion, and a second connector structure at the second tube end portion. Exemplary connector structures include male and female flare connectors, and male pipe thread connectors.
In accordance with another aspect of the invention, a method of fabricating a sweep elbow tube connector is described, comprising the steps of:
providing an injection mold structure defining exterior features of a tube connector member comprising a first linear tube end portion, a second linear tube end portion, and a curved sweep tube portion defined by a relatively large sweep radius, the mold structure including a curved first core pin for defining an interior passageway portion of the tube connector member in the curved sweep tube portion and of the first linear tube end portion, and a straight second core pin for defining an interior passageway portion of the tube connector member in the second linear tube end portion;
injecting a molten plastic material in a cavity formed in the mold structure to form the tube connector, wherein the tube connector member has a thick wall thickness over at least a portion of the curved sweep tube portion and a thin wall thickness over the first linear tube end;
removing the second core pin from the mold structure;
after the plastic material has hardened to form a solid part, removing the solid part from the mold structure with the first core pin still in place in the solid part; and
stripping the first core pin from the solid part by effecting relative movement therebetween, the solid plastic material forming the first linear tube end flexing to allow withdrawal of the curved core pin.